The use of cellular telephones within cellular telephone networks has substantially advanced the convenience and mobility of communication between users of telephones. However, as with many advances in technology, limitations often present themselves, which in turn create new frustrations and new opportunities to deal with those frustrations. One not-uncommon frustration among telephone users is when, during an ongoing telephone call that involves a cellular telephone, the signal strength to or from that cellular telephone has dropped sufficiently to cause an abrupt, unexpected loss of call (also known as a “dropped call”).
Although improvements in cellular telephone networks and cellular telephones themselves have helped limit such dropped call occurrences within given regions and systems, the abrupt, unexpected loss of call remains a problem for many cellular telephone users. This also presents a problem for the landline parties with whom they communicate. Often, one party may continue speaking, not realizing the call already has terminated. That party, as well as one or more parties on the same call, frequently feel frustration due to an unexpected interruption of the call. Efforts often are made to call back the other party or parties to inform them of that the call was unintentionally dropped. Upon reconnecting at a later time, time and effort are required to establish the last thing the other party heard in order to efficiently continue the conversation.
Certain approaches are known in the art to help warn such telephone users of a possible loss of call due to insufficient cellular telephone signal strength. For example, U.S. Pat. No. 6,018,655, issued Jan. 25, 2000 to Bartle and Erickson, discloses methods of analyzing various conditions of cellular telephone operation, and then, when a specific predefined threshold is met for a particular condition, notifying the user that a communication disconnection is imminent. Among the conditions disclosed are count/rate communications such as frame validity, frame quality, symbol quality, and chip quality. Transmitter output level and received signal strength indication (RSSI) are other conditions measured and analyzed.
According to the disclosure of U.S. Pat. No. 6,018,655, if an error rate has been detected by the analysis of conditions (i.e., data for a condition has exceeded its threshold), a control system of the digital telephone system attempts to improve the quality of the audio signals based on the analysis of conditions. Also, under such circumstance a warning process ensues. For example, if the RSSI falls below a fixed threshold level, then a warning signal is generated to advise the cellular telephone user. This warning may be delayed, in certain embodiments, until two consecutive threshold violations have occurred, in order to reduce the likelihood of an erroneous warning.
U.S. Pat. No. 6,330,438, issued Dec. 11, 2001 to McClelland and Madison, recognizes the problem of communications signal strength that is too low to continue a call. When there is no other cell to hand off to, in order to sustain adequate signal strength, the user of a mobile cell phone unit is alerted to the low signal situation. This is stated to provide the user with time to take precautionary steps, such as the user moving or re-orienting the mobile cell phone unit in order to improve signal reception. In order to determine when to provide an audible warning prior to losing such an in-progress call, the received signal level is compared to a predetermined threshold level. If the received signal level falls below the predetermined threshold level, and there is not another cell to which to hand off the call, then an audible signal is generated to warn the cell phone user. U.S. Pat. No. 6,018,655, U.S. Pat. No. 6,330,438, and all other patents, all patent applications, all patent publications, and all other publications cited herein are incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually set forth in its entirety, and are particularly incorporated by reference for the teachings disclosed herein.
The above approaches suffer from the comparison to a predetermined, fixed threshold, the crossing of which is the criteria for the signal to user of a possibly imminent dropped call. Also, these approaches do not provide for warning of parties other than the user whose cell phone has the disclosed features. Even when the user of the relevant cell phone receives the warning signal, he or she may not have enough time to complete a verbal statement to the call's other party or parties to inform them of the likelihood of a dropped call.
The present invention more fully addresses the problems associated with low-signal-strength-based dropped calls and overcomes the shortcomings of the above approaches. The methods, systems and apparatuses of the present invention provide superior advisory alerts to the parties involved in a telephone call that involves at least one cellular telephone, including the user of that cellular telephone.